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--- ffmpeg:conversions:convert_h264_to_av1:libaom:constant_quality [2023/06/13 22:11] – created peter
+++ ffmpeg:conversions:convert_h264_to_av1:libaom:constant_quality [2023/06/14 07:04] (current) – peter
@@ Line 1: / Line 1: @@
 ====== ffmpeg - Conversions - Convert H264 to AV1 - libaom - Constant Quality ======
+**libaom-av1** has a constant quality (CQ) mode (like CRF in x264 and x265) which will ensure that every frame gets the number of bits it deserves to achieve a certain (perceptual) quality level, rather than encoding each frame to meet a bit rate target.
+  * This results in better overall quality.
+  * If you do not need to achieve a fixed target file size, this should be your method of choice.
+----
+<code bash>
+time ffmpeg -i a.mp4 -c:v libaom-av1 -crf 30 -f mp4 out.mp4
+</code>
+returns:
+<code bash>
+...
+real	260m18.018s
+user	1514m33.124s
+sys	0m43.892s
+</code>
+<WRAP info>
+**NOTE:**
+  * Input test size:  75.5M
+  * Output test size:  24.5M
+</WRAP>
+<WRAP info>
+**NOTE:**
+  * **crf**:  This value can be from 0–63.
+    * Lower values mean better quality and greater file size.
+    * 0 means lossless.
+    * A CRF value of 23 yields a quality level corresponding to CRF 19 for x264 (source), which would be considered visually lossless.
+</WRAP>